One of the most exciting things on the 3D printing horizon is printing in silicone, a rubbery and extremely versatile polymer which has wide applications in virtually all industries. Many 3D printing and materials companies have been making headway within the field of 3D printing silicone, such as German companies WACKER and Keyence, for instance, though there is still much left to be accomplished, especially in the desktop 3D printing community.

That is why we were very excited to hear about an innovative new project realized by a team of students from the Delft University of Technology in The Netherlands, who have developed a 3D printer add-on that allows for silicone to be cast into a 3D printed shell during the printing process. While the new technology is not “3D printing silicone” per se, it is a promising inroad into more accessible and customizable silicone casting.

The new method, which was presented at the Advanced Prototyping science fair of the university’s faculty of Industrial Design Engineering, is called UltiCast and essentially combines 3D printing with more traditional molding and casting techniques which are standard for silicone. In other words, the machine works by simultaneously 3D printing a plastic shell or mold and filling said shell with a two-component silicone mix.

The students have even created a specialized code which automatically slices the 3D printed mold and determines exactly how much silicone mix must be used to fill it. If you’re wondering how to remove the silicone from the shell, the team has used PVA to 3D print the shells, a material which can easily be dissolved in water.

To develop the UltiCast technology, the team of students used an Ultimaker 3D printer, which they hacked and rebuilt almost entirely. With their modified device, they have proven that they can create complex molds for silicone—not entirely new itself—but can also cast the silicone at the same time.

As the team suggests, their new method could have useful applications in the field of soft robotics, as it could allow for the quick and cheap manufacturing of soft actuators. As Rob Scharff, an UltiCast team member and soft robotics PhD candidate, explains, “You get a lot of freedom to personalize the behavior of robots with geometry and materials.” This includes making flexible robot limbs, and custom-designed grippers, which could allow for more versatile robotic movements. Using UltiCast it is even possible to 3D print a harder material inside the silicone, which could allow for even more complex parts and materials.

The new technology could also prove to be useful within the medical sector, where soft robotics have a role to play. More specifically, UltiCast could be a useful tool in the creation of movement aids, such as 3D printed gloves with soft robotic actuators which could help those suffering from debilitating conditions such as local paralysis, arthritis, or injuries. “Reducing the cost of treatment and support utilities is a goal that inspires us all. Soft robotics could, in the long term, be a big player in the progress,” the team commented.

Impressively, the UltiCast 3D printer add-on was developed on the cheap, as the current iteration of it was made for only about €3000. For what is essentially a rudimentary multi-material 3D printing system, that is a price to write home about. For now, however, UltiCast is more a proof of concept than anything, and is still far from being a commercially viable product. In fact, it is not clear whether the students will even pursue the development of the novel system.

Whether they do or not, UltiCast is still an interesting experiment within the field of multi-material 3D printing and soft robotics. As the student team has shown, 3D printing limits can easily be broken down, and innovation is never far away.